1. Field of the Invention
The present invention relates to the field of packaging of sterile or oxygen-sensitive products, such as medical products and food products. More particularly, the present invention is directed to methods and arrangements for packaging oxygen-sensitive items, whereby a change in appearance of a material visually indicates the presence of oxygen inside the packaging. Additionally, the present invention relates generally to the field of vascular medical devices. More specifically, the present invention relates to a gas inflation/evacuation system and sealing system for selectively and repeatedly inflating an occlusive balloon and crimping an extended sealable section proximate the proximal end of a guidewire assembly during an occlusion procedure.
2. Description of the Prior Art
In certain applications, such as pharmaceutical storage or food processing, it is desirable to package the product in a controlled atmosphere or environment to ensure freshness, to promote proper chemical activity, or to prevent microbial contamination. The controlled atmosphere can be an inert gas such as nitrogen or carbon dioxide, or it could be a noble gas. In some applications, the controlled environment could be a vacuum. In those applications where a controlled atmosphere or environment is desirable, it may be beneficial to be able to determine that the desired controlled atmosphere or environment has not been compromised. The presence of oxygen in a previously evacuated sample indicates that atmospheric penetration has occurred and that the controlled atmosphere has been compromised. Thus, oxygen detection is one method for determining if a controlled atmosphere has been breached.
In the medical and food processing industries, it may be desirable to sterilize medical and food products after these products have been placed inside containers with controlled environments. The medical and food processing industries have sterilized some appropriate products with gamma radiation. Gamma radiation, which can be derived from cobalt 60, is lethal to bacteria and other microorganisms due to the effect that the radiation has on living cells. In addition, gamma radiation can be detrimental to some chemical systems and compositions. The dose or amount of radiation absorbed is typically measured in either Megarads or Kilograys, where 1 Megarad is equivalent to 10 Kilograys. In general, a 2.5 Megarad, or 25 Kilogray, dose of gamma radiation can be sufficient to kill most microorganisms.
Gamma radiation is composed of high energy photons with wavelengths generally shorter than about 0.1 nm. Gamma radiation is emitted from atomic nuclei during radioactive decay and generally follows the ejection of beta rays from the nucleus. X-rays are similar to gamma rays in the sense that both are highly energetic and penetrating forms of radiation. However, gamma rays usually have shorter wavelengths than X-rays, and as a result, gamma rays are slightly higher in energy than X-rays.
As a result of the increased use of gamma radiation sterilization and packaging in controlled environments, there is a need for oxygen-sensitive materials that can be placed inside medical and food product containers which can detect the presence of oxygen after the container has been irradiated, and possibly sterilized, with gamma radiation.
Currently, there are several types of oxygen, and oxidation, sensors designed to be used in packaging applications. See, for example, U.S. Pat. No. 4,526,752 to Perlman et al., U.S. Pat. No. 5,096,813 to Krumhar et al., U.S. Pat. No. 6,399,387 to Stenhom et al., and U.S. Pat. No. 6,325,974 to Ahvenainen et al. However, none of these patents are directed toward oxygen-sensitive materials that are activated by radiation. Furthermore, the above mentioned sensors are not suitable to form component parts for other devices. With the volume of medical devices and food products being produced, it would be desirable to provide an oxygen sensor that was easily stored in oxygen-rich environments and could be activated upon exposure to gamma radiation in the absence of oxygen.
The following additional background may be of assistance in understanding the present invention. Arterial disease involves damage that happens to the arteries in the body. Diseased arteries can become plugged with thrombus, plaque, or grumous material that may ultimately lead to a condition known as ischemia. Ischemia refers to a substantial reduction or loss of blood flow to the heart muscle or any other tissue that is being supplied by the artery and can lead to permanent damage of the affected region. While arterial disease is most commonly associated with the formation of hard plaque and coronary artery disease in the heart, similar damage can happen to many other vessels in the body, such as the peripheral vessels, cerebral vessels, due to the buildup of hard plaque or softer thrombus or grumous material within the lumen of an artery or vein.
A variety of vascular medical devices and procedures have been developed to treat diseased vessels. The current standard procedures include bypass surgery (where a new blood vessel is grafted around a narrowed or blocked artery) and several different types of nonsurgical interventional vascular medical procedures, including angioplasty (where a balloon on a catheter is inflated inside a narrowed or blocked portion of an artery in an attempt to push back plaque or thrombotic material), stenting (where a metal mesh tube is expanded against a narrowed or blocked portion of an artery to hold back plaque or thrombotic material), and debulking techniques in the form of atherectomy (where some type of high speed or high power mechanism is used to dislodge hardened plaque) or thrombectomy (where some type of mechanism or infused fluid is used to dislodge grumous or thrombotic material). In each of these interventional vascular medical procedures, a very flexible guidewire is routed through the patient's vascular system to a desired treatment location and then a catheter that includes a device on the distal end appropriate for the given procedure is tracked along the guidewire to the treatment location.
Although interventional vascular procedures avoid many of the complications involved in surgery, there is a possibility of complications if some of the plaque, thrombus or other material breaks free and flows downstream in the artery or other vessel, potentially causing a stroke, a myocardial infarction (heart attack), or other tissue death. One solution to this potential complication is to use some kind of occlusive device to block or screen the blood flowing downstream of the treatment location. Examples of catheter arrangements that use a pair of balloons as occlusive devices to create an isolated space in the blood vessel are described in U.S. Pat. Nos. 4,573,966, 4,636,195, 5,059,178, 5,320,604, 5,833,644, 5,925,016, 6,022,336 and 6,176,844. Examples of catheter arrangements that use a single balloon as an occlusive device either upstream or downstream of the treatment location are described in U.S. Pat. Nos. 5,171,221, 5,195,955, 5,135,482, 5,380,284, 5,688,234, 5,713,917, 5,775,327, 5,792,179, 5,807,330, 5,833,650, 5,843,022, 6,021,340, 6,159,195 and 6,248,121. An example of a catheter arrangement that uses a mechanically-expanded occlusive device is shown in U.S. Pat. No. 6,231,588. Occlusive balloons also have been used on non-over-the-wire catheters without any guidewire internal to the catheter as described, for example, in U.S. Pat. Nos. 4,838,268 and 5,209,727.
The use of an occlusive device as part of a vascular procedure is becoming more common in debulking procedures performed on heart bypass vessels. Most heart bypass vessels are harvested and transplanted from the saphenous vein located along the inside of the patient's leg. The saphenous vein is a long, straight vein that has a capacity more than adequate to support the blood flow needs of the heart. Once transplanted, the saphenous vein is subject to a buildup of plaque or thrombotic materials in the grafted arterial lumen. Unfortunately, the standard interventional vascular treatments for debulking are only moderately successful when employed to treat saphenous vein coronary bypass grafts. The complication rate for a standard balloon angioplasty procedure in a saphenous vein coronary bypass graft is higher than in a native vessel with the complications including embolization, “no-reflow” phenomena, and procedural related myocardial infarction. Atherectomy methods including directional, rotational, and laser devices are also associated with a high degree of embolization resulting in a greater likelihood of infarction. The use of stents for saphenous vein coronary bypass grafts has produced mixed results. Stents provide for less restenosis, but they do not eliminate the risk of embolization and infarction incurred by standard balloon angioplasty.
In order to overcome the shortcomings of these standard nonsurgical interventional treatments in treating saphenous vein coronary bypass graft occlusion, embolic protection methods utilizing a protective device distal to the lesion have been developed. The protective device is typically a filter or a balloon. Use of a protective device in conjunction with an atherectomy or thrombectomy device is intended to prevent emboli from migrating beyond the protective device and to allow the embolic particles to be removed, thereby subsequently reducing the risk of myocardial infarction. When the occlusive device is a balloon, the balloon is inserted and inflated at a point distal to the treatment site or lesion site. Therapy is then performed at the treatment site and the balloon acts to block all blood flow which prevents emboli from traveling beyond the balloon. Following treatment, some form of particle removal device must be used to remove the dislodged emboli prior to balloon deflation. U.S. Pat. No. 5,843,022 uses a balloon to occlude the vessel distal to a lesion or blockage site. The occlusion is treated with a high pressure water jet, and the fluid and entrained emboli are subsequently removed via an extraction tube. U.S. Pat. No. 6,135,991 describes the use of a balloon to occlude the vessel allowing blood flow and pressure to prevent the migration of emboli proximally from the treatment device.
There are various designs that have included an occlusive balloon on the end of a guidewire. U.S. Pat. Nos. 5,520,645, 5,779,688 and 5,908,405 describe guidewires having removable occlusive balloons on a distal end. U.S. Pat. No. 4,573,470 describes a guidewire having an occlusive balloon where the guidewire is bonded inside the catheter as an integral unit. U.S. Pat. Nos. 5,059,176, 5,167,239, 5,520,645, 5,779,688 and 6,050,972 describe various guidewires with balloons at the distal end in which a valve arrangement is used to inflate and/or deflate the balloon. U.S. Pat. No. 5,908,405 describes an arrangement with a removable balloon member that can be repeatedly inserted into and withdrawn from a guidewire. U.S. Pat. No. 5,776,100 describes a guidewire with an occlusive balloon adhesively bonded to the distal end with an adapter on the proximal end to provide inflation fluid for the occlusive balloon.
Except in the case of the normal cerebral anatomy where there are redundant arteries supplying blood to the same tissue, one of the problems with using an occlusive device in the arteries is that tissue downstream of the occlusive device can be damaged due to the lack of blood flow. Consequently, an occlusive device that completely blocks the artery can only be deployed for a relatively short period of time. To overcome this disadvantage, most of the recent development in relation to occlusive devices has focused on devices that screen the blood through a filter arrangement. U.S. Pat. Nos. 5,827,324, 5,938,672, 5,997,558, 6,080,170, 6,171,328, 6,203,561 and 6,245,089 describe various examples of filter arrangements that are to be deployed on the distal end of a catheter system. While a filter arrangement is theoretically a better solution than an occlusive device, in practice such filter arrangements often become plugged, effectively turning the filter into an occlusive device. The filter arrangements also are mechanically and operationally more complicated than an occlusive balloon device in terms of deployment and extraction.
As is the case in almost all angioplasty devices or stenting catheter devices where a balloon is used to expand the blood vessel or stent, most catheter occlusive balloons, as well as most guidewire occlusive balloons, utilize a liquid fluid, such as saline or saline mixed with a radiopaque marker, for fluoroscopic visualization (i.e., contrast) as the inflation medium. Generally, a liquid fluid medium for expanding vascular balloons has been preferred because the expansion characteristics of a liquid are more uniform and predictable, and because a liquid medium is easier to work with and more familiar to the doctors. In the case of angioplasty balloons, for example, high pressure requirements (up to 20 atmospheres) necessitate that the inflation fluid be an incompressible fluid for safety reasons. While having numerous advantages, liquid fluids do not lend themselves to rapid deflation of an occlusive balloon because of the high resistance to movement of the liquid in a long small diameter tube. In the context of angioplasty procedures, the balloon catheter has a much larger lumen than a guidewire. Consequently, rapid deflation is possible. In the context of a guidewire, however, liquid-filled occlusive balloons typically cannot be deflated in less than a minute and, depending upon the length of the guidewire, can take up to several minutes to deflate. Consequently, it is not practical to shorten the period of total blockage of a vessel by repeatedly deflating and then re-inflating a liquid-filled occlusive balloon at the end of a guidewire.
Gas-filled balloons have been used for intra-aortic occlusive devices where rapid inflation and deflation of the occlusive device is required. Examples of such intra-aortic occlusive devices are shown in U.S. Pat. Nos. 4,646,719, 4,733,652, 5,865,721, 6,146,372, 6,245,008 and 6,241,706. While effective for use as an intra-aortic occlusive device, these occlusive devices are not designed for use as a guidewire as there is no ability to track a catheter over the intra-aortic occlusive device.
An early catheter balloon device that utilized a gas as an inflation medium and provided a volume limited syringe injection system is described in U.S. Pat. No. 4,865,587. More recently, a gas-filled occlusive balloon on a guidewire is described as one of the alternate embodiments in U.S. Pat. No. 6,217,567. The only suggestion for how the guidewire of the alternate embodiment is sealed is a valve-type arrangement similar to the valve arrangement used in a liquid fluid embodiment. A similar gas-filled occlusive balloon has been described with respect to the Aegis Vortex™ system developed by Kensey Nash Corporation. In both U.S. Pat. No. 6,217,567 and the Aegis Vortex™ system, the gas-filled occlusive balloon is used for distal protection to minimize the risk of embolization while treating a blocked saphenous vein coronary bypass graft. Once deployed, the occlusive balloon retains emboli dislodged by the atherectomy treatment process until such time as the emboli can be aspirated from the vessel. No specific apparatus are shown or described for how the gas is to be introduced into the device or how the occlusive balloon is deflated.
Although the use of occlusive devices has become more common for distal embolization protection in vascular procedures, particularly for treating a blocked saphenous vein coronary bypass graft, all of the existing approaches have significant drawbacks that can limit their effectiveness. Liquid-filled occlusive balloons can remain in place too long and take too long to deflate, increasing the risk of damages downstream of the occlusion. Occlusive filters are designed to address this problem, but suffer from blockage problems and can be complicated to deploy and retrieve and may allow small embolic particles to migrate downstream. Existing gas-filled occlusive balloons solve some of the problems of liquid-filled occlusive balloons, but typically have utilized complicated valve and connection arrangements. It would be desirable to provide for an occlusive device that was effective, simple, quick to deploy and deflate, and that could overcome the limitations of the existing approaches.
It would be even more desirable if a medical device, such as an inflation/deflation system and a sealing system for occlusive balloons which systems are intended for use with a biocompatible gas and intended to avoid oxygen exposure could be stored and then used with confidence that they have not been exposed to oxygen. Moreover, it would be still more desirable if any unintended oxygen exposure could be readily visually detected immediately upon opening a sealed container in the course of medical treatment.